Our solar panels occupy only a third of our roof area. Even so, on a summer day they produce about the same power our Volkswagen electric car draws as it charges from a plug in the garage. So, to the extent that we top up during the day, we are literally driving on sunshine: nil

Panasonic Corp. sees the future of solar on car rooftops. The Osaka-based electronics maker has started producing a 180-watt array of solar cells that can be fixed to the roof of an automobile. In February, Panasonic announced that its photovoltaic module would be used on the roof of Toyota Motor Corp.’s latest Prius plug-in hybrid.